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Theimportantthingaboutaproblemisnotitssolution,butthestrengthwegaininfindingthesolution.---AnonymousChapter6CapacitorsandInductors6.1Introduction6.2Capacitors6.3SeriesandParallelCapacitors6.4Inductors6.5SeriesandParallelInductors6.1IntroductionResistors:dissipate(消耗)energyCapacitors,Inductors:storeenergy(storageelement)Whyshouldwestudycapacitorsandinductors?Theapplicationofresistivecircuitsisquitelimited.Typicalapplicationwithopamp:Integrators(积分器)Differentiators(微分器)6.2CapacitorsDielectric:介质(电介质)Permittivity:介电常数Metalplate:金属面板Insulator:绝缘体Parallel-platecapacitor:平行板电容器Acapacitorconsistsoftwoconductingplatesseparatedbyaninsulator(ordielectric)ACdisthecapacitanceofacapacitor,withunitoffarad(F)whereCCircuitSymbols:(a)Fixedcapacitors(b)VariablecapacitorsivCivCCommontypesoffixed-valuecapacitors:(a)Polyestercapacitors聚酯电容器(b)Ceramiccapacitors陶瓷电容器(c)Electrolyticcapacitors电解电容器Commontypesofvariablecapacitors:(a)Trimmercapacitors可调电容器(b)Filmtrimcapacitors薄膜可调电容器Functionofcapacitors:blockDC,passAC,shiftphase,storeenergy,startmotors,suppressnoiseCurrent-voltagerelationshipofthecapacitors:qvqqCvdqidtdviCdtSlopeCidvdtor1tvidtC001()ttvidtvtCand00()where()qtvtCThecapacitorhasmemoryInstantaneouspower:dvpviCvdt212tttttdvwpdtCvdtCvdvCvdtsince()0vEnergystored:212wCvthenor22qwCAidealcapacitorcannotdissipateenergyKeepinmind1.AcapacitorisanopencircuittoDC.(However,ifabatteryisconnectedacrossacapacitor,thecapacitorcharges)2.Thevoltageonacapacitorcannotchangeabruptly.(Adiscontinuouschangeinvoltagerequiresaninfinitecurrent,whichisphysicallyimpossible)3.Theidealcapacitordoesnotdissipateenergy,butexchangeenergywithsource.4.Areal,nonidealcapacitorhasaparallel-modelleakageresistance(泄漏电阻).leakageresistanceCircuitmodelofanonidealcapacitors:6.3SeriesandParallelCapacitors123Niiiii1231NNkeqkdvdvdvdviCCCCdtdtdtdtdvdvCCdtdtParallel:1C2C3CNCi1i2i3iNivBut.Hence,kkdviCdt123whereeqNCCCCCieqCv123NvvvvvSeries:001But()().Therefore,tktkvitdtvtC1C2C3CNCi1v2v3vNvv00000102001210200120111()()()()()()111()()()()1()()tttNtttNtNtNtteqvitdtvtitdtvtitdtvtCCCitdtvtvtvtCCCitdtvtC12311111eqNwhereCCCCC010200()()()()NvtvtvtvtExampleFindthevoltageacrosseachcapacitorforthefollowingcircuit.1v2v3v30V20mF30mF40mF20mF1C2C3C4CSolution:12341111eqCCCCC111112030402010eqC10eqCmF3Thetotalchargeis1010300.3eqqCvCTherefore,1310.3152010qvVC2320.3103010qvVC312305vvvVAssignment1.Solvethepracticeproblem6.7inpage2116.4Inductors(横截面)(圈数)Aninductorconsistsofacoilofconductingwire.2NALlWhereListheinductanceofaninductor,withunitofhenry(H),(磁导率)CircuitSymbols:(a)Air-coreinductors(b)Iron-coreinductors(b)VariableinductorsCommontypesofinductors:(a)Solenoidalwoundinductors螺旋管型电感器(b)Toroidalinductors环形电感器(c)Chipinductors片式电感器Current-voltagerelationshipoftheinductors:divLdt1()tivtdtL001()()ttivtdtitLTheinductorhasmemoryInstantaneouspower:dipviLidt212tttttdiwpdtLidtLidiLidtEnergystored:since()0i212wLithenKeepinmind1.AinductoractslikeashortcircuittoDC.2.Thecurrentthroughaninductorcannotchangeinstantaneously.(Adiscontinuouschangeinthecurrentthroughaninductorrequiresaninfinitevoltage,whichisphysicallyimpossible.However,thevoltageacrossaninductorcanchangeabruptly.)3.Theidealinductordoesnotdissipateenergy,butexchangeenergywithsource.4.Apractical,nonidealinductorhaswindingresistance(Rw)andwindingcapacitance(Cw).Circuitmodelofanonidealinductors:LwRwC6.5SeriesandParallelInductors123NiiiiiParallel:001But().Hence,tkktkivdtitLiv1i2i3iNi1L2L3LNLeqLiv00000102001210200012111()()()1111()()()()tttNtttNttNttNeqivdtitvdtitvdtitLLLvdtitititvdtitLLLL12311111whereeqNLLLLL010200()()()()Nitititit1231NNkeqkdidididivLLLLdtdtdtdtdidiLLdtdtSeries:But.Hence,kkdivLdt123whereeqNLLLLLv1v2v3vNvieqLiv123NvvvvvImportantcharacteristicsofthebasicelements6.6ApplicationRCiiIntegratorThena0vivR0RiCi0A0VCAtnodea:0But,iRCvdviiCRdt0ivdvCRdt01idvvdtRC0001()(0)()tivtvvtdtRC0Assuming(0)0v001()()tivtvtdtRCRCiiDifferentiatorThenAtnodea:0But,iRCvdviiCRdt0ivdvCRdt0idvvRCdta0vivR00A0VCRiCiAssignment1.Solvethepracticeproblem6.54and6.61inpages233-234
本文标题:电路原理课件讲义英文版-Chapter-6
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